1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
2. College of Nursing, Rush University Medical Center, Chicago, Illinois
3. John H. Stroger, Jr, Hospital of Cook County, Chicago, Illinois
4. Section of Emergency Medicine, University of Chicago, Chicago, Illinois
5. Centers for Disease Control and Prevention, Atlanta, Georgia
6. Institute for Healthcare Studies, Northwestern University Feinberg School of Medicine, Chicago, Illinois
7. Midwest Center for Health Services and Policy Research and Hines Veterans Affairs Hospital, Hines, Illinois